Amplification - Amplification: DI Box

Leggi questa pagina in Italiano Lire cette page en Franšais
CDROM Multimedia Audio Course Enjoying this Course?
Download the full version!

There are audio signal generators that have very high internal impedance values, and are therefore difficult to manage with common amplifiers. A high internal impedance means in fact a loss of voltage on the transferred signal; very rarely will an amplifying stage have an input impedance which equals at least 10 times the one inside the signal generator. This is indeed the case with electric guitar and bass guitar pick-ups, which therefore cannot be connected directly to the input of an amplifier (i.e a mixer channel's preamplifier).

For such a scope, a circuit comes into play called DI box, that brings about an impedance adaptation without losses on the signal's amplitude. The DI box has a high input impedance (which allows the signal to be picked up free from any deterioration) and a low output impedance (which allows for optimal transfers of the received signal to the amplifier). The following diagram shows the action of the DI box when connecting an electric guitar to a mixer channel:

Amplification - Amplification of an electric guitar using a DI box

Amplification of an electric guitar using a DI box

The main role of the DI box is to bring about an impedance adaptation. This is true for all signals called line signals, those issuing from keyboards, synthesizers, samplers.

Another function of the DI box is to transform the connection from unbalanced to balanced [Electric connections ] . An example is an electric guitar's signal which is picked up with an unbalanced lead with 1/4" jacks at its ends, and plugged into the DI box. From here the signal becomes balanced and since the impedance has also changed, it can be connected to the mixer's microphone input through a microphone lead. This way the mixer's line inputs are used for other purposes, like the effects returns used by the sound engineer, whilst in the meantime all the signals issued far away from the mixer arrive with a balanced connection. When the signal is sent through long cables, it's worthwhile using balanced connections to obtain far higher quality in the signals we receive.


Read alla about Audiosonica-Wikipedia integration Related topics on Wikipedia


Latest Comments


Latest Posts


Most visited